Consider the following six relations for an order-processing database application in a company:

CUSTOMER (Cust#, Cname, City)

ORDER (Order#, Odate, Cust#, Ord_Amt)

ORDER_ITEM (Order#, Item#, Qty)

ITEM (Item#, Unit_price)

SHIPMENT (Order#, Warehouse#, Ship_date)

WAREHOUSE (Warehouse#, City)

Ord_Amt refers to total dollar amount of an order.

Odate is the date the order was placed.

Ship date is the date an order is shipped from the warehouse.

Assume that an order can be shipped from several warehouses.

1. Give an update operation to a database state that violates a key constraint, stating any assumptions on the database state you make.
2. Give an update operation to a database state that violates an entity integrity constraint, stating any assumptions on the database state you make.
3. Give an update operation to a database state that violates a referential integrity constraint, stating any assumptions on the database state you make.
4. Give an update operation to a database state that violates an integrity constraint that is neither of the previous kinds of constraints, stating any assumptions you make.
5. Specify foreign keys for this schema, stating any assumptions you make.